I did my work experience stints at a primary school - good fun because you see what it's like on the other side and the young kids look up to you like a hero! Get to run sports time, have fun on yard duty playing with kids and a godo feeling when you actually teach someone something! lol
If you're interested in a legal career the Law Society offers work experience but as others have said it'll basically be admin stuff so you'd be better off going somewhere where you get to actually do something for yourself....
at my school they didnt call it work experience, it was structured workplace learning or SWL for short. it wasnt compulsory and essentially it was a way to get the dropkicks interested in earning money so that they would leave the school. since 2005 (the year i was MEANT to graduate) they have had a 100% graduation rate.
PS i never did SWL